Author: Nagendra Singh Tomar
Date: 16:39:15 10/28/02
I am using iterative deepening with transposition tables. Suppose at some point in the match I have a board that is say stored in hash with stored depth 10. So when iterative deepening searches that position with increasing depth, till depth 10 hash_probe will return the stored position and so alphabeta returns instantly. Since I am not using some hash2pv kind of function, I get a PV length of 1 with the best hash move being on the PV. But now when the iterative deepening searches for depth 11, the (stored_depth>= depth) clause is not true inside hash_probe and hence it does not return the stored position. Now alphabeta is on its own with no PV to help it order the moves (just some help from the hash inmove ordering). In such cases my program takes an unusually *long* time to search the next iteration (11th in this example). This reminds me of the days when I was not using iterative deepening and searching to a fixed depth. Is this normal behaviour, or dies it say something about the inefficiency of the hash ? What do we do to avoid this ? regds tomar
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